1. Field of the Invention
The present invention relates to a process for manufacturing many of the common commercial elastomers. The elastomers that can be manufactured by this process include, but are not limited to, ethylene-propylene-diene rubber, styrene-butadiene rubber, styrene-butadiene thermoplastic rubber, cis-polybutadiene rubber, butyl rubber and cis-polyisoprene rubber. The process applies to both batch and continuous manufacturing processes. Further, the process is used with elastomers produced in solution or in particulate form. A modification of the process makes it applicable for the manufacture very low molecular weight liquid polymers.
2. Description of the Prior Art
The manufacture of elastomers in anhydrous solvents or diluents consists of a polymerization section, a catalyst removal section, an elastomer particulation section, a diluent and monomer recycle purification section and an elastomer packaging and shipping section. See, for example for unrelated types of processes, U.S. Pat. No. 3,523,929, entitled "Olefin Polymerization Process", issued Aug. 11, 1970, to J. L. Paige et al; U.S. Pat. No. 2,565,960, entitled "Preparation of an Improved Hydrocarbon Resin", issued Aug. 28, 1951, to J. D. Garber et al; U.S. Pat. No. 4,068,053, entitled "Method of Removing Water From Liquid Olefin In The Polymerization of Olefins", issued Jan. 10, 1978, to C. D. Miserlis et al.
Existing elastomer processes do not normally use fine molecular sieve removal steps prior to the reactor in the polymerization section, although the use of molecular sieves is known in the art. Various purification steps for other processes unrelated to the elastomer process of this invention are shown in the prior art. See, for example, U.S. Pat. No. 2,900,430, entitled "Process For the Removal of straight Chain Acetylene From Isoprene", issued Aug. 18, 1959, to A. M. Henke et al; U.S. Pat. No. 2,906,795, entitled "Recovery and Utilization of Normally Gaseous Olefins", issued Sep. 29, 1959, to W. P. Bullard et al; U.S. Pat. No. 3,209,050, entitled "Purification of Diolefins", issued Sep. 28, 1965, to E. S. Hanson; U.S. Pat. No. 3,326,999, entitled "Purification of Olefins", issued Jun. 20, 1967, to R. D. Rhodes, Jr.; U.S. Pat. No. 3,352,840, entitled "Removal of Deposits From Polymerization Reactors", issued Nov. 14, 1967, to C. M. Oktay; U.S. Pat. No. 3,514,426, entitled "Process For Suppressing Molecular Jump", issued May 26, 1970, to R. E. Barrett; U.S. Pat. No. 3,635,931, entitled "Polyisoprene From Amylenes Via-Amylene Isomerization Oxidative Dehydrogeneration Extractive Distillation and Polymerization of Low-Concentration Isoprene", issued Jan. 18, 1972, to J. W. Davison; U.S. Pat. No. 4,016,349, entitled "Process For Removing Vanadium Residues From Polymer Solutions", issued Apr. 5, 1977, to J. M. McKenna; U.S. Pat. No. 4,182,801, entitled "Method of Drying Liquid Olefin Monomer Feed in a Molecular Sieve Dryer in the Polymerization of Olefins From Liquid Olefin Monomer", issued Jan. 8, 1980, to Miserlis et al; U.S. Pat. No. 4,235,983, entitled "Purification of Olefin Recycle to Polymerization", issued Nov. 25, 1980, to Steigelmann et al; and Paige.
Existing processes utilize an expensive hot water injection particulation section which also increases the cost of diluent and monomer recycle purification and adds a water waste disposal problem.
The use of flashing or settling zones for recovery of materials in processes unrelated to the elastomer process of this invention is also known in the prior art. See, for example, U.S. Pat. No. 2,921,053, entitled "Recovery of Olefins From Hydrocarbon Mixtures", issued Jan. 12, 1960, to R. F. Dye; and McKenna.
Further, some patents show the use of additives for product separation. See, for example, U.S. Pat. No. 4,098,980 to Markle et al. As set out infra, the reactants and other materials are carefully specified, and no additional additives, or place from which they could be introduced, are shown in the specification, and the process operates as shown and without any such additives.